CN101111912B - Method and device for determining a switching time of an electric switching device - Google Patents

Abstract

The invention relates to a method and device for determining a switching time of an electric switching device. An electric switching device comprises an interrupter link (1). A first line section (2) and a second line section (3) can be connected and disconnected by means of said interrupter link (1). In order to determine a switching time, the temporal progression of a driving voltage (A) is determined in the first line section (2). In addition, a temporal course of an oscillator voltage (B, B1) appearing in the second line section (2) is determined. Potential switching times are determined at the voltage zero crossings of a resulting voltage (C, C1). The selection of the potential switching times ensues while evaluating the rises of the driving voltage (A, A1) and of the oscillator voltage (B, B1) or of the polarity of the oscillating current (D).

Description

The method and apparatus that is used for the switching time of definite electric switching system

Technical field

The present invention relates to a kind of method and apparatus that is used for the switching time of definite electric switching system, this electric switching system has the contact maker circuit, and it is arranged between first conducting line segment that has been applied in working voltage and second conducting line segment that constitutes oscillating circuit after the disconnection process of this switchgear.

Background technology

By document " Analysis of Power System Transients Using Wavelets and PronyMethod ", Lobos, T., Rezmer, J., Koglin, H.-J., Power Tech Proceedings, 2001IEEEPorto, 10～13, draw September calendar year 2001, and quality of voltage has more and more important meaning in the electric energy transmitting network.The waveform of alternating voltage should be sine-shaped in the ideal case, and with predetermined frequency and amplitude vibration.But because instantaneous overvoltage may appear in inductance and/or capacity cell in switching process.This instantaneous overvoltage is superimposed upon on the rated frequency and specified amplitude of desirable alternating voltage, thereby disturbs the voltage change process of expectation.

Switch process is the superpotential incident of triggering for generating normally.

Summary of the invention

Therefore the technical problem to be solved in the present invention provides the method and apparatus that is used for determining switching time, is limited in by them to occur instantaneous overvoltage or oscillatory occurences in the electric energy transmitting network.

Start in the method for described type at this paper, technical problem of the present invention solves like this, wherein, determine the time-varying process of the disconnection process working voltage afterwards of electric switching system, determine the time-varying process of the oscillating voltage of appearance after the disconnection process of electric switching system, determine time-varying process corresponding to the voltage as a result of the difference of working voltage and oscillating voltage, analyze at least one slope of this working voltage and at least one slope of oscillating voltage, and according to described slope and as a result the time-varying process of voltage determine switching time.

Technical problem of the present invention in addition also solves like this, wherein, determine the time-varying process of the disconnection process working voltage afterwards of electric switching system, determine the time-varying process of the oscillating voltage of appearance after the disconnection process of electric switching system, determine the time-varying process of the oscillating current that after the disconnection process of electric switching system, in oscillating circuit, flows through, determine time-varying process corresponding to the voltage as a result of the difference of described working voltage and oscillating voltage, analyze at least one polarity of at least one slope and the oscillating current of this working voltage, and according at least one slope of working voltage, at least one polarity of oscillating current and as a result the time-varying process of voltage determine switching time.

Formed voltage as a result may be because assembly that comprises in the oscillating circuit such as coil and capacitor have the obvious voltage amplitude higher than working voltage.This is especially because inductance and electric capacity are the memory elements that generation time postpones.This may cause the obviously too high of peak value for disadvantageous combination.This very high voltage peak plays negative effect to insulation system.Thereby insulation is heavier in burden aspect the dielectric than under measuring condition.What this caused insulating is faster aging.Especially the conducting line segment such as the cable of isolating for solid may damage the life-span.Voltage peak may be high to produce arcing on lead under extreme case.This arcing for example can be expressed as partial discharge or the puncture on the maintenance insulator of the long distance of wire of isolating free air.This phenomenon is harmful especially in insulation system that solid is isolated such as cable, because may form the damage that can not repair at this.Therefore the time-varying process of voltage is applicable to the important criterion of the switching time of determining electric switching system as a result.Can optimize the selection of switching time in addition, wherein consider working voltage slope, be the upstroke slope of upstroke slope and the oscillating voltage that in oscillating circuit, forms.Respectively at the change procedure of specific moment observed result voltage, and analyze the change procedure of oscillating voltage or working voltage at synchronization at this.According to the slope of working voltage or oscillating voltage and the time-varying process of voltage as a result, can determine the switching time of the appearance of over-voltage especially effectively.Except the slope of analyzing working voltage and oscillating voltage, can also adopt the slope (upstroke slope) of working voltage and the polarity conduct of oscillating current to be used for determining the choice criteria of the switching time of the change procedure of voltage as a result on the principle.Therefore can make the oscillating voltage that drives oscillating current pass through equation according to the impedance that in oscillating circuit, forms

Intercouple.

For determine working voltage, oscillating voltage and as a result voltage or oscillating current time-varying process and adopt diverse ways.Thereby for example can in first conducting line segment and second conducting line segment, the time-varying process that measurement mechanism is used to gather desired parameters be set respectively.On the respective wire section, for example adopt the voltage and current converter for this reason.In order to limit the quantity of curtage converter, can also only adopt single converter, and from transducer data, calculate the curtage change procedure that is lacked respectively.

Thereby image data is also determined corresponding voltage/current change procedure in real time in the equipment of corresponding equipment, and definite switching time.The slope of voltage change process for example can carry out in the difference of corresponding moment of interest by this time-varying process.By electronic data processing equipment, can in the shortest time, determine at first derivative of each any time almost, thereby determine the slope of working voltage or oscillating voltage.Both can distinguish at this and to have gathered this slope quantitatively, thereby obtain in the change procedure of this slope trend like a cork from the time interval to a next time interval.Can also only analyze slope quantitatively, that is to say to have positive slope or negative slope, in other words conj.or perhaps above still being lower than specific limiting value.The polarity of electric current can relate to its quantity ground equally to be analyzed, and that is to say, can determine the value of oscillating current according to absolute value and phase place.Can only make such asserting in addition: the oscillating current that occurs in specific moment have on the occasion of or have negative value.

Preferred implementation of the present invention can also be that described switching time is positioned at the near zero-crossing point of described voltage as a result.

In large-scale technical equipment, adopt an alternating voltage or a plurality of alternating voltage that phase shift is arranged each other usually in same system as working voltage.Have a plurality of systems of the alternating voltage of relation that exist each other and be also referred to as the polyphase ac electrical voltage system.The working voltage that applies voltage to first conducting line segment typically has constant frequency.Preferred 162/3Hz, 50Hz, 60Hz and other frequency range of adopting in large-scale technology.Owing in oscillating circuit, exist superposition phenomenon, oscillating voltage to have frequency different and different peak values here with working voltage by memory element or the triggering of the element of time of delay that comprises.In the scope of the zero crossing of voltage as a result, the minimum overvoltage of supposition appears in the switching process respectively.Therefore the zero crossing of voltage as a result is chosen as preferred switching time.

Preferably, can also be the near zero-crossing point of switching time selection result voltage, have the identical slope of direction implication at this zero crossing working voltage and oscillating voltage.

Another preferred implementation is, is the near zero-crossing point of switching time selection result voltage, has negative slope at this zero crossing working voltage, and oscillating current has positive polarity, and perhaps working voltage has positive slope and oscillating current has negative polarity.

Described voltage as a result has many voltage over zero.This illustrate, some in these voltage over zero are switching times more favourable than other.The criterion that is used for the suitable voltage over zero of selection result voltage is the slope of working voltage and the slope of oscillating voltage.If the slope of the slope of working voltage and oscillating voltage has identical direction implication when zero crossing of voltage as a result, then this zero crossing especially is suitable as switching time.Identical slope is that working voltage and oscillating voltage have positive slope respectively or have negative slope respectively in this meaning.In addition, the digital absolute value of this slope can also be introduced in the analysis, and be determined switching time more exactly thus.

Because oscillating voltage and certain relation and can conversion mutually on calculating is arranged in oscillating circuit, therefore do not analyze the slope of oscillating voltage and change the polarity of analyzing oscillating current into by the oscillating current that oscillating voltage drives.Specially suitable switching time is the zero crossing of voltage as a result, has negative slope and oscillating current has positive polarity at this zero crossing working voltage, perhaps has positive slope and oscillating current has negative polarity at this zero crossing working voltage.To be analysis to the analytic transformation of oscillating voltage to oscillating current, be the analysis that is transformed to polarity, because owing to the inductance that comprises in oscillating circuit and electric capacity have been passed about 90 degree between making in AC power system in electric current and voltage change process.

Another preferred implementation is that described oscillating current flows through corrector choke.

In the electric energy transmitting network, for example adopt arbitrary routing of line.At the arbitrary routing of line of direct high pressure with between the earth potential under this arbitrary routing of line, form capacitive means.This arbitrary routing of line can be used as capacitor work thus, and introduces corresponding bearing power in this arbitrary routing of line.In order to limit this bearing power, so-called corrector choke can be set in the process of arbitrary routing of line.This corrector choke is the coil with corresponding inductance, and can compensate the condenser type load that produces by arbitrary routing of line.This choke can constitute dissimilarly, thereby for example can be connected to ground as required, and is perhaps also can its inductance variable.Preferably, beginning and the end at arbitrary routing of line all adopts the choke that can insert.Replacedly, such combination can also in the ground cable system, occur, promptly in this combination, between electric conductor and cable joint-box, form corresponding condenser type resistance.Determine the size of the oscillating current in second conducting line segment together by corrector choke.Owing to the element of necessary being and because the Ohmic resistance that the conductor material that is adopted exists produces the effective resistance loss, magnetic transition loss etc., thus oscillating current or oscillating voltage are decayed in second conducting line segment.

Another preferred implementation distortion is that the time-varying process of described oscillating voltage and/or oscillating current is determined by the Prony method.

Contact maker circuit closure in the switchgear of connecting.The first conducting line segment drive current with working voltage flows to second conducting line segment.This working voltage for example produces by the generator in the power station.Because this voltage shows as driving voltage, this voltage also propagates in second conducting line segment.In second conducting line segment, connect customer usually.Customer can for example be motor, firing equipment or can also be complete electrical network section, as electric power consumed by industry device or a large amount of apparatus for household use.After the disconnection process, working voltage only also exists in first conducting line segment, because the contact maker circuit disconnects, and working voltage can not appear in second conducting line segment again.In first conducting line segment, typically have energy-producing device, as have the power supply grid of the operation in corresponding generator or power station.In the second electrical network section, has the combination of ohm, inductance and condenser type parts corresponding to it, because the unexpected separation of contact maker circuit and time of bringing thus change the oscillating voltage that forms the driving oscillating current.The time-varying process of working voltage fixes on really that this is fairly simple, because can be from the rigidity electrical network, working voltage be to be close to the characteristic variable that keeps constant in this rigidity electrical network.Problematic is to determine the oscillating current in the oscillating circuit or the time-varying process of oscillating voltage.In order to obtain corresponding elimination run, the reliable change procedure prediction at the time interval in one or more future is determined in expectation in advance from the measured value of determining in short time interval.For example adopt the Prony method for this reason.

The Prony method is with respect to other method-as the following advantage of Laplace conversion-provide: the further change procedure that just can dope voltage and current according to a spot of measured value more exactly.

The Prony method is applicable to particular form and realizes controlled switch, has nothing to do with the fundamental oscillation of expectation because compare section sweep time of existing voltage and/or current data with Fourier transform.Phase shift and the decay that can obtain each frequency component arbitrarily during this external use Prony method.In order to use the Prony method at first to obtain the voltage and/or the current data that exist in the described electrical network constantly in difference.For this reason from a N complex data point x[1 of the incident of sinusoid or exponential damping arbitrarily]] ... x[n] set out.This data point must be equally spaced data point.Scanning process can by p exponential function and describe:

$y\left[n\right]=\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{A}_k\exp [({\mathrm{\&alpha;}}_k+\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="H2006800036079E00021.png,H2006800036079E00031.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}{f}_k)(n-1)T+j{\mathrm{\&theta;}}_k],---\left(2.1\right)$

Wherein

T-is the scan period of unit with s

A _kThe amplitude of-plural index

α _k-with s ^-1Attenuation coefficient for unit

f _k-be the pure oscillation frequency of unit with Hz

θ _k-be the phase shift of unit with the radian.

In the process of actual scanning be with plural decomposing index have equal amplitude to grip plural number altogether right.This has reduced equation (2.1) concerning 1≤n≤N:

$y\left[n\right]=\underset{k=1}{\overset{p/2}{\mathrm{\&Sigma;}}}2A_k\exp \left[{\mathrm{\&alpha;}}_k(n-1)T\right]\cos [2\mathrm{\&pi;}{f}_k(n-1)T+{\mathrm{\&theta;}}_k]---\left(2.2\right)$

If the number of exponential function p is an even number, then there be p/2 cosine function that is attenuated.If its number is an odd number, then there is the very exponential function of underdamp of the cosine function of (p-1)/2 decay and.

By the parameter that makes up the parameter relevant and have nothing to do, obtain the more simply expression of equation (2.1) with the time with the time:

$y\left[n\right]=\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-1}---\left(2.3\right)$

h _k＝A _k?exp(jθ _k) (2.4)

z _k＝exp[(α _k+j2πf _k)T] (2.5)

Parameter h _kBe complex amplitude and be and constant that the time is irrelevant.Plural number index z _kBe the parameter relevant with the time.

In order to describe true process, the mean square error ρ on N the number of scans strong point need be minimized by summation.

$\mathrm{\&rho;}=\underset{n=1}{\overset{N}{\mathrm{\&Sigma;}}}{\left|\mathrm{\&epsiv;}\right[n\left]\right|}^2---\left(2.6\right)$

$\mathrm{\&epsiv;}\left[n\right]=x\left[n\right]-y\left[n\right]=x\left[n\right]-\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-1}---\left(2.7\right)$

This is minimized in considers parameter h _k, z _kWith carry out under the condition of p.It causes a very difficult nonlinear problem, even the number of p is known (referring to Marple, Lawrence:DigitalSpectral Analysis, London:Prentice-Hall International, 1987) to this exponential function.A kind of may be the method for solving (Newton method) of iteration.But this is to be prerequisite with very big computing capability, because must often carry out inverse transformation to the matrix greater than the data point number.Adopt the Prony method in order effectively to address this problem, it uses linear equality to find the solution.In this method, decompose the non-linear aspect of considering exponential function by polynomial factor.There is the rapid solving algorithm for this class factor decomposition.

The Prony method

For approximate change procedure, need obtain a lot of data points and come to determine uniquely parameter.This means needs x[1 at least respectively] ..., x[2p] individual complex data point:

$x\left[k\right]=\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-1}.---\left(2.8\right)$

Can observe, adopt x[n] replace y[n].This is that they are corresponding to having 2p complex parameter h because need 2p complex data point just _kAnd z _kExponential model.This pass ties up in the equation (2.6) and expresses by minimizing square error.

In equation (2.8), express the target of Prony algorithm.This equation provides for being illustrated in detail in the equation (2.9) of 1≤n≤p.

If know the element z in this matrix, then provide a plurality of linear equalities, utilize these equatioies can calculate complex amplitude vector h.

As the principle of this method for solving, be even linear solution of difference equation with constant coefficients based on equation (2.8).In order to find separating of corresponding equation, at first define the multinomial φ of even number p _{P (z)}:

φ _p(z)＝a[0]z ^p+a[1]z ^p-1+...+a[p-1]z+a[p] (2.10)

Parameter z to be determined has provided this polynomial zero point.

This polynomial table is shown and carries out (equation 2.11) by algebraical basic principle.Coefficient a[m] be plural number, and definition a[0]=1.

${\mathrm{\&phi;}}_p\left(z\right)=\underset{m=0}{\overset{p}{\mathrm{\&Sigma;}}}a\left[m\right]z^{p-m}---\left(2.11\right)$

By the subscript of equation (2.8) from n move to n-m and with parameter a[m] acquisition of multiplying each other:

$a\left[m\right]x[n-m]=a\left[m\right]\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-m-1}---\left(2.12\right)$

If form simple product (a[0] x[n] ..., a[m-1] x[n-m+1]) and, then obtain from equation (2.12) with they additions:

$a\left[0\right]x\left[n\right]=a\left[0\right]\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-1}$

$a\left[1\right]x[n-1]=a\left[1\right]\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-2}$

$a\left[2\right]x[n-2]=a\left[2\right]\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-3}---\left(2.13\right)$

$\begin{array}{c}\&CenterDot;\\ \&CenterDot;\\ \&CenterDot;\end{array}$

$a\left[m\right]x[n-m]=a\left[m\right]\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-m-1}$

$\underset{m=0}{\overset{p}{\mathrm{\&Sigma;}}}a\left[m\right]x[n-m]=\stackrel{\&OverBar;}{\underset{m=0}{\overset{p}{\mathrm{\&Sigma;}}}\left[a\right[m\left]\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}{h}_k{z}_k^{n-m-1}\right]}$

The right by conversion equation (2.13) obtains:

$\underset{m=0}{\overset{p}{\mathrm{\&Sigma;}}}a\left[m\right]x[n-m]=\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}\left[h_k\underset{m=0}{\overset{p}{\mathrm{\&Sigma;}}}a\right[m\left]z_k^{p-m-1}\right].---\left(2.14\right)$

By deducting $z_i^{n-m-1}=z_i^{n-p}{z}_i^{p-m-1}$ Obtain:

$\underset{m=0}{\overset{p}{\mathrm{\&Sigma;}}}a\left[m\right]x[n-m]=\underset{k=1}{\overset{p}{\mathrm{\&Sigma;}}}\left[h_k{z}_k^{n-p}\underset{m=0}{\overset{p}{\mathrm{\&Sigma;}}}a\right[m\left]z_k^{p-m-1}\right]=0.---\left(2.15\right)$

This and the right can see multinomial again from equation (2.11).By determining all root z _kObtain zero point of being searched.Equation (2.15) is the linear difference equation of being searched, and it is separated is exactly equation (2.8).Multinomial (2.11) is the feature equation of this difference equation.

P equation represented a[m] feasible value, they untie equation (2.15).

In equation (2.16), there be p unknown number.Matrix x is made up of p+1 row and column.Therefore equation (2.16) is an overdetermination.In order to obtain solution vector, the top row of the x matrix that disappears and known coefficient a[0], and deduct first row:

Can determine p unknown number by p equation.

The Prony method can comprehensively be 3 steps.

Solve equation (2.17)

Obtain the coefficient of multinomial (2.11)

The root of evaluator (2.11)

Obtain the parameter z relevant by equation (2.8) with the time _k

Calculate decay and frequency by z:

α _k＝ln|z _k|/T (2.18)

f _k＝tan ^-1[Im(z _k)/Re(z _k)]/[2πT] (2.19)

Launch equation (2.9)

According to finding the solution of h

Calculate amplitude and phase shift:

A _k＝|h _k| (2.20)

θ _k＝tan ^-1[Im(h _k)/Re(h _k)] (2.21)

Estimation for the future time change procedure does not need to determine each parameter." prediction " to the further change procedure of input signal also can be by parameter z _kAnd h _k, the variation of equation (2.8) and variable n is carried out, and this variation has reflected time range to be estimated.But when the time step width of this estimation changes to some extent with respect to scanning, must clearly determine decay, frequency, amplitude and these parameters of phase shift.

Another advantage that the Prony method is used to analyze electric current and/or voltage change process is that this method also can be used for the process of higher frequency.The process of higher frequency is interpreted as the process of vibrating in the scope of 100-700Hz.The running frequency scope comprises the frequency between 24 to 100Hz.24Hz is interpreted as lower frequency.High-frequency process for example occurs when the switchgear switch.High fdrequency component is superimposed upon in the fundamental oscillation.

In addition preferably, voltage that obtains in order to handle and/or current data and use the Prony method of correction.

Prony method and the maximum likelihood principle (Gauss principle of least square) revised are similar.When calculating, set out from a fixing p (number of exponential function is referring to top).Carry out alternative manner in the computing interval, optimize the accuracy of pre-determined voltage and/or electric current change procedure thus.Realize definite accuracy by determining that the tolerance limit of optimizing can be changed.Can shorten needed computing time according to different requirements thus.The Prony method of revising is at Osborne, Smyth:A modified Prony Algorithm for fittingfunctions defined by difference equation, SIAM Journal of Scientific and StatisticalComputing, Vol.12,362-382 has obtained detailed introduction among the March 1991.The Prony method of revising is insensitive for the voltage of determining from the electric energy net and/or " noise " of current data.This " noise " is inevitable when using real assembly to determine voltage and/or current data.This interference has only and just can reduce to minimum by bigger cost.By the robustness of " noise " of opposing input signal, when using the Prony method of revising, can adopt measuring equipment with low cost to determine voltage and/or the current data that occurs in the electrical network.

Can be provided for carrying out the device of said method, it has the device that uses automatic processes voltage of Prony method and/or current data.

Because the process investigated is just finished in several milliseconds interval, therefore to have the device that is used for automatic processes voltage and/or current data be favourable to described device.In order to carry out the processing of automation especially apace, the device wiring programming ground that is used for handling automatically can be implemented.Sort circuit is known as specific to the integrated circuit of using " ASIC ".If but being provided for the enough fast device of processing automatically, then this device memory can be implemented able to programmely.The programmable device that is used for handling automatically of sort memory can come to be complementary with the boundary condition of conversion by reprogramming simply.

Another preferred embodiment is, is applied to voltage on the contact maker circuit corresponding to voltage as a result after the disconnection process.

The contact maker circuit must cause as far as possible apace respectively in being switched on or switched off process that infinite-impedance from perfect condition is to infinitely small impedance or opposite impedance conversion.Ideally this is that great-jump-forward ground forms.But not like this in technological system of the present invention.But adopt the switch element of the contact with relative motion in high pressure range, these contacts are positioned at insulating gas.Insulating gas preferably is in the sulphur hexafluoride under the pressure of increase.In the connection process, for example before the electric contact in relatively-movable contact, just caused the appearance of pre-arcing.In the disconnection process, after disconnecting electric arc, cancellation needs certain firm time again, the electric arc cancellation gas that is polluted that during this period of time forms in switching circuit is removed from this switching circuit and is replaced by untainted insulating gas, and described disconnection electric arc may form after the overall separation of relatively-movable contact.

The voltage as a result that forms by the contact maker circuit is provided by the working voltage of an end that is positioned at this contact maker circuit and the oscillating voltage that is positioned on the other end of this contact maker circuit.As mentioned above, owing to can postpone by generation time when oscillatory process occurring in oscillating circuit, therefore obviously higher absolute value of voltage of the measured value that can guess than working voltage may appear on this contact maker circuit.Therefore the described voltage as a result that forms on the contact maker circuit of electric switching system is the important parameter that is used for the switching time of definite electric switching system.Overtension also must reliably be controlled by electric switching system.

Preferably, can also when determining described switching time, consider the pre-arcing feature of described switchgear at this.

Except determining preferred switching time, be also noted that real switchgear has pre-arcing feature.But before the contact of the contact of two relative motions, the dielectric between the contact is just by arc through.Power switch tends to the sort of mode and produces composition and the change procedure that pre-arcing depends on the switch motion.Ideally this pre-arcing should not exist, and that is to say respectively to carry out the Mechanical Contact of contact and the closure of circuit at autotelic controlled time of contact.But this ideal situation can't reach in practice, thereby there is so-called pre-arcing characteristic curve in a switchgear.This characteristic curve has certain gradient, can discern the intersection point between this characteristic curve and the change in voltage curve sometimes.This moment, pre-arcing also can take place in the contact that does not also have electric contact.

Another preferred embodiment is, is determining under the situation of oscillating voltage and/or oscillating current decay in advance that described switching time is near any zero crossing of voltage as a result.

Owing to be included in the real elements in the oscillating circuit,, the decay of oscillating voltage or oscillating current in this oscillating circuit, occur as capacitor, coil and Ohmic resistance.If this decay no longer includes meaning to the collection that makes measuring technique by force, then can abandon to the slope of oscillating voltage or working voltage with to the analysis of the polarity of oscillating current.Then in order to realize high-speed switch,, and connect at the next possible zero crossing of voltage as a result as long as also adjust to the zero crossing of voltage as a result.Under the situation that continues attenuated oscillation voltage or oscillating current, the too high effect of voltage can be left in the basket on the contact maker circuit of electric switching system.

In addition preferably, the connection process that switching time is used for electric switching system.

Adopt so-called protection equipment in the electric energy transmitting network, it starts the disconnection process of electric switching system automatically when breaking down.Usually should the disconnection process trigger by the fragmentary fault that occurs.Some fragmentary faults that occur make to reclose fast and become possibility.A kind of typical sporadic fault for example is positioned at the arbitrary routing of line zone.Object, for example the branch on the tree triggers the short circuit on the lead.But the incident that should trigger short circuit only continues the very short time, and therefore (air insulation between lead and the branch rebulids, and short circuit event is gone over) can reclose this lead after this fault is eliminated.This connection is also referred to as automatically and recloses (AWE).This recloses automatically in 300 to about 500ms time period and finishes, and that is to say after electric switching system successfully disconnects, and the automatic reclosing that starts this switchgear in the time of maximum 300 (500) ms is logical.Because this time interval is shorter, therefore form very high oscillating voltage or oscillating current in the oscillating circuit that can form at this moment.Especially for reclosing automatically or switchgear connection in the short time after successfully disconnecting,, determine that suitable switching time is very important for fear of owing to the overtension on the contact maker circuit of electric switching system causes arcing.Need not limit superpotential resistance on electric switching system, perhaps the scale of this resistance can be very little.

In addition, the invention still further relates to a kind of equipment that is used to carry out described method.

The present invention is can the selector switch moment in this task that this equipment is proposed.

According to the present invention, this solves in the equipment that is used for carrying out according to each described method of claim 1 to 11 like this, and described equipment has the device of the polarity of the slope that is used for comparison working voltage and oscillating voltage and/or oscillating current.

Potential switching time of some when the device that is used for the polarity of the slope of comparison working voltage and oscillating voltage and/or oscillating current makes the voltage over zero that can simply be chosen in voltage as a result.The result of this comparison for example can relate to whether to allow switching process is or does not judge.

Description of drawings

Describe the embodiment of the invention in the accompanying drawing below in detail.

This illustrate:

Fig. 1 is the schematic diagram with optimized switch voltage change process constantly,

Fig. 2 is the schematic construction of electric energy transmitting network,

Fig. 3 is the change procedure of two Different Results voltages,

Fig. 4 is the change procedure of different voltage and currents,

Fig. 5 is the change procedure of different voltages,

Fig. 6 illustrates the time flow that is used for determining following voltage/current change procedure,

When being illustrated in capacitive load, Fig. 7 considers pre-arcing feature,

Fig. 8 is illustrated in the use to pre-arcing characteristic curve under the situation of the contact maker line inductance load of electric switching system,

Fig. 9 is the device that is used for comparison one column voltage change procedure.

Embodiment

Fig. 1 is exemplary, and frequency is shown is that the sinusoid of the alternating voltage of 50Hz changes process.For fear of forming overvoltage, should distinguish when the voltage max of sinusoidal-shaped voltage change procedure, insert as much as possible inductive load (5ms constantly, 15ms).On the contrary, should be respectively when a point of zero voltage, insert capacitive load, with avoid on the capacitor charging process (0ms constantly, 10ms, 20ms).

In real electric energy transmitting network, only observe the desirable formation of sinusoidal-shaped voltage change procedure under special circumstances.

The theory structure of the conducting line segment in the electric energy transmitting network shown in Figure 2.Electric switching system has contact maker circuit 1.But this contact maker circuit is for example formed by the contact of two relative motions.Can interconnect or separate by contact maker circuit 1 first conducting line segment 2 and second conducting line segment 3.First conducting line segment 2 has generator 4.Generator 4 provides working voltage, and it for example is the alternating voltage of the 50Hz of ployphase voltages system.Second conducting line segment 3 has arbitrary routing of line 5.Arbitrary routing of line 5 can be connected with first choke 6 of ground potential 7 at its first end, is connected with earth potential 7 by second choke 9 at its second end.Another choke 9 can be connected with second choke 8 in addition.Can be connected with earth potential 7 according to different distortion by different switchgears 10 chokes 6,8,9.Can come with different degree compensation arbitrary routing of lines 5 according to loading condition thus.Thereby may be by the inductance resistance X of choke _L(X _L=j ω L) comes the capacitance resistance X of overcompensation or undercompensation arbitrary routing of line _c(X _c=1/ (ω c)).By the capacitance resistance Xc of arbitrary routing of line and the inductance resistance X of all chokes _LresRelation, can determine degree of compensation k.For degree of compensation k is set, choke 6,8,9 differently can be interconnected.But can also make choke have adjustable inductance resistance X _LFor example can adopt adjustable iron core choke for this reason.

In second conducting line segment 3, after disconnecting contact maker circuit 1, can form an oscillating circuit by earth potential 7.Must form corresponding current path by the switchgear 10 of ground potential 7 in order in second conducting line segment 3, to form oscillating circuit.Form oscillating circuit by inductance resistance and capacitance resistance, and the oscillating current that in this oscillating circuit, flows and drive by oscillating voltage.

The voltage change process as a result that forms on contact maker circuit 1 for different degree of compensation exemplarily is shown in Fig. 3.When compensation k=0.8, formation has the specific frequency change process of a plurality of voltage over zero.This frequency change process has beat.Be compensated for as at 0.3 o'clock, form corresponding different frequency change process, but this frequency change process still having a plurality of voltage over zero.

When adopting the inventive method, can reduce the connection resistance that exists for over-voltage at present, or can abandon this resistance fully.Owing to determine best reclosing constantly, can realize better switch result, that is to say, than littler instantaneous overvoltage under any slave mode, occurring with electric switching system of connecting resistance.

Fig. 4 be illustrated in adopt working voltage A, oscillating voltage B, as a result under the condition of voltage C and oscillating current D to the analysis of the switching time of electric switching system with determine.Working voltage A is with constant frequency and uniform amplitude vibration.The oscillating voltage B that forms in the oscillating circuit of second conducting line segment 3 is with specific frequency and variable amplitude vibration, and wherein this frequency is variable.This change is because the extra stack that decay occurs and outer flow may occur in the system.In the stack of working voltage A on appearing at first conducting line segment 2 and the oscillating voltage B that second conducting line segment 3, forms, form the time-varying process of voltage C as a result.Voltage C is corresponding to the voltage that applies on the contact maker circuit that disconnects as a result.Obviously can identify in Fig. 4, voltage C vibrates with obvious variable amplitude as a result, and there are phase shift in working voltage A and oscillating voltage B.Potential switching time is present on the voltage over zero of voltage C as a result.In order to discern voltage over zero better, in the change procedure of voltage C as a result, mark with circle.But whether as a result all voltage over zero of voltage C all are applicable to the process that recloses of contact maker circuit 1.As choice criteria, in example shown in Figure 4, also introduce the polarity of oscillating current D.For identification better, respectively with+or-mark the polarity of oscillating current D in the corresponding interval between the current zero-crossing point of oscillating current D.The positive polarity of oscillating current D and the positive slope of working voltage A occur at first voltage over zero of voltage D as a result, that is to say that first voltage over zero 1 of voltage C is not suitable for the connection process as a result.The negative slope of working voltage A occurs at the 4th voltage over zero of voltage C as a result, and oscillating current D has positive polarity, that is to say that in these voltage over zero the 4th of voltage C the voltage over zero is particularly useful for the process of reclosing as a result.At this first and the 4th voltage over zero is exemplary introducing.Can exist other voltage over zero to be particularly useful for causing the connection process of contact maker circuit 1 in addition.These voltage over zero may be present in the interval shown in Figure 4, also may be outside these intervals.

The system of selection of replacement shown in Figure 5, wherein A1 represents the time-varying process of working voltage, and B1 represents the time-varying process of oscillating voltage, and C1 represents the voltage as a result on the interrupter unit.Voltage C1 is drawn by the potential difference that is applied to the working voltage A1 on first conducting line segment 2 and be applied between the oscillating voltage B1 on second conducting line segment 3 of contact maker circuit 1 as a result.The zero crossing of voltage C1 still is potential switching time as a result.For the only voltage over zero of selection result voltage C1 is analyzed respectively at these slopes (gradient of rising) constantly.At moment t1, working voltage A1 and oscillating voltage B1 have negative slope, that is to say that this is particularly suitable for the process of reclosing constantly.At moment t2, working voltage A1 has negative slope and oscillating voltage C1 has positive slope, that is to say constantly t2 and as a result voltage C1 be not suitable for the process of reclosing at the zero crossing that moment t2 occurs.Can come other each zero crossing classification of voltage as a result according to working voltage and the oscillating voltage slope under respectively in addition, thus obtain a result voltage other be fit to and be not suitable for the zero crossing of the process of reclosing.

Scanning X shown in Figure 6, the time series of calculating Y, checking Z, calculate U once more and be used to trigger the time interval of V.Once to reclose automatically in order in 300 to about 500ms, for example carrying out, to determine the voltage change process of voltage as a result in advance.Disconnect the contact maker circuit of electric switching system in moment t=0ms supposition at this.In first 50ms, the scanning or the time-varying process of definite working voltage, formed oscillating voltage and oscillating current, and determine voltage as a result according to the voltage change process of working voltage.In 50 to 100ms the time interval, calculate the following time-varying process of oscillating voltage or oscillating current, calculate the following time-varying process of voltage as a result thus.In 100 to 150ms the time interval can with the oscillating voltage that calculates, oscillating current or as a result the value of the time-varying process of voltage, working voltage compare with the value that truly forms.Be positioned in the value of confirming to calculate and think that signal change procedure has obtained correct calculating in advance when checking set time window.For this calculated example as adopting Prony method or similar approach.Stagger the time in the calculating in advance of determining this time-varying process, 150 to 200ms the time interval can be used in addition, in this time interval, by voltage in the true electrical network that in 0 to 150ms the time interval, obtains or electric current change procedure, can recomputate following voltage or electric current change procedure.Because time interval of 0 to 150ms is bigger, and the number of measurement values that exists like this is more, therefore can calculating more accurately from the following time-varying process of curtage.According to the polarity of the oscillating current of the slope of the slope of the voltage over zero of voltage as a result and oscillating voltage and working voltage or working voltage and formation, can determine desirable switching time.Can carry out temporal prerun to discharge triggering signal according to this switching time now, wherein can consider the pre-arcing characteristic curve of the contact maker circuit 1 that adopted, thus at the latest 300 or 500ms after moment of being restricted of overtension in the electric energy transmitting network carry out reclosing of this interrupter unit.When the exemplary time-varying process that illustrates among Fig. 4 and Fig. 5 be time-varying process in an extremely short time interval (50ms or shorter) precompute the time, can reclose especially smoothly.Pre-determine by this and to have realized the enough prerun time that during this period of time all essential stand-by period or prerun time can be passed through the clock feed-in.Thereby for example can plan out to provide the needed time of this signal location to trigger equipment at electric switching system with contact maker circuit 1 from producing triggering signal.It is also conceivable that the pre-arcing feature of contact maker circuit 1 in addition.Therefore can carry out synchro switch more accurately.

The pre-arcing feature 11 of contact maker circuit 1 is shown respectively in Fig. 7 and Fig. 8.Pre-arcing feature 11 is reduced to the change procedure of the linearity with certain slope at this.In Fig. 7, connect a capacitive load, for example also do not had the cable that loads.As shown in Figure 1, preferably should in voltage over zero, connect capacitive load.Pre-arcing feature 11 is precipitous like this at this, makes voltage change process fall into a voltage over zero in the ideal case with the intersection point of pre-arcing feature 11.In corresponding more flat pre-arcing feature 11a, the focus of pre-arcing feature 11a and voltage change process is greatly about moment 5ms place, that is to say in this moment just to have formed pre-arcing, but therefore occur the desirable moment in advance the conduct current voltage over zero.Adopt the electric switching system of pre-arcing feature thus with steeper for the ideal connection process of capacitive load.Among the embodiment with pre-arcing feature 11 shown in Figure 7, the electric contact of contact and pre-arcing appear at 10ms constantly together, thereby have realized that electric switching system does not almost have superpotential switch.

In example shown in Figure 8, connected an inductive load.But pre-arcing feature 11 is precipitous like this, promptly must form the intersection point between pre-arcing feature 11 and the voltage change process.At moment 5ms, between the contact of the motion of contact maker circuit 1, produce electric arc and form pre-arcing.But the contact in moment 7.6ms relative motion is in contact with one another.

By in conjunction with the arcing feature of method of the present invention, can effectively prevent the superpotential appearance of switch in switching process with the electric switching system of noting being adopted.

Fig. 9 illustrates the theory structure of the equipment that is used to carry out this method.

This equipment has the device 12 of the slope that is used for comparison working voltage A and oscillating voltage B.Output signal 13 when fixing ratio appears in these slopes.

Claims (18)

1. method that is used for determining the switching time of electric switching system, this electric switching system has contact maker circuit (1), it is arranged on first conducting line segment (2) that has been applied in working voltage (A1) and constitutes after the disconnection process of this switchgear between second conducting line segment (3) of oscillating circuit, it is characterized in that

Determine the time-varying process of the disconnection process working voltage (A1) afterwards of electric switching system,

Determine the time-varying process of the oscillating voltage that after the disconnection process of electric switching system, in oscillating circuit, occurs,

Determine time-varying process corresponding to the voltage as a result (C1) of the difference of described working voltage (A1) and oscillating voltage (B1),

Analyze at least one slope of this working voltage (A1) and at least one slope of oscillating voltage (B1), and according to these at least two slopes and as a result the time-varying process of voltage (C1) determine switching time.

2. method according to claim 1 is characterized in that, described switching time is positioned at described voltage as a result (C, near zero-crossing point C1).

3. method according to claim 1 is characterized in that, is the near zero-crossing point of described switching time selection result voltage (C1), has the identical slope of direction implication at this zero crossing working voltage (A1) with oscillating voltage (B1).

4. method according to claim 1 is characterized in that, after the disconnection process, be applied on the contact maker circuit (1) voltage corresponding to described voltage as a result (C, C1).

5. method according to claim 1 is characterized in that, considers the pre-arcing feature of described switchgear when determining described switching time.

6. method according to claim 1 is characterized in that, (B, (C is near any zero crossing C1) at voltage as a result B1) to determine in advance described switching time under the situation of decay at oscillating voltage.

7. according to each described method in the claim 1 to 6, it is characterized in that described switching time is used for the connection process of described electric switching system.

8. method that is used for determining the switching time of electric switching system, this electric switching system has contact maker circuit (1), it is arranged on first conducting line segment (2) that has been applied in working voltage (A) and constitutes after the disconnection process of this switchgear between second conducting line segment (3) of oscillating circuit, it is characterized in that

Determine the time-varying process of the disconnection process working voltage (A) afterwards of electric switching system,

Determine the time-varying process of the oscillating voltage (B1) of appearance after the disconnection process of electric switching system,

Determine after the disconnection process of electric switching system the time-varying process of the oscillating current (D) that in oscillating circuit, flows,

Determine time-varying process corresponding to the voltage as a result (C) of the difference of described working voltage (A) and oscillating voltage (B),

Analyze at least one polarity of at least one slope and the oscillating current (D) of this working voltage (A), and according at least one polarity of at least one slope of working voltage (A), oscillating current (D) and as a result the time-varying process of voltage (C) determine switching time.

9. method according to claim 8 is characterized in that, described switching time is positioned at described voltage as a result (C, near zero-crossing point C1).

10. method according to claim 8, it is characterized in that, near zero-crossing point for switching time selection result voltage (C), has negative slope at this zero crossing working voltage (C), oscillating current (D) has positive polarity, and perhaps working voltage (C) has positive slope and oscillating current (D) has negative polarity.

11. method according to claim 10 is characterized in that, described oscillating current flows through corrector choke (6,8,9).

12. method according to claim 8 is characterized in that, described oscillating voltage (B, B1) and/or the time-varying process of oscillating current (D) determine by the Prony method.

13. method according to claim 8 is characterized in that, after the disconnection process, be applied on the contact maker circuit (1) voltage corresponding to described voltage as a result (C, C1).

14. method according to claim 8 is characterized in that, considers the pre-arcing feature of described switchgear when determining described switching time.

15. method according to claim 8 is characterized in that, oscillating voltage (B, B1) and/or determine described switching time under the situation of oscillating current (D) decay in advance (C is near any zero crossing C1) at voltage as a result.

16. each described method in 15 is characterized in that described switching time is used for the connection process of described electric switching system according to Claim 8.

17. an equipment that is used to implement according to the described method of claim 1 is characterized in that described equipment has the device (12) of the polarity of the slope that is used for comparison working voltage and oscillating voltage.

18. an equipment that is used to implement according to the described method of claim 8 is characterized in that, described equipment has the device (12) of the polarity of the slope that is used for comparison working voltage and oscillating voltage or oscillating current.

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